Rotary pump



June 14, 1932. A, v, JENSEN 1,863,160

ROTARY PUMP Original Filed Oct. 21, 1929 INVENTOR .Am as Verner Janae n,

ag-md ATTORNEY Patented June 14, 1932 UNITED STATES PATENT OFFICE mos VERNER JENSEN, or CEDAR rALL's, IOWA, ASSIGNOR 'ro VIKING ZPUMP comrm,

or CEDAR FALLS, IOWA ROTARY PUMP Original application filed October 21, 1929, Serial No. 401,191. Divided and this application filed August 28,

1930. Serial No. 477,333.

My invention relates to improvements in rotary pumps and motors, and the ob ect of my improvement is to provide release means for entrapped liquids in such devlces to reduce wear of the rotating parts, reduce power consumption, increase mechanlcal efficiency of the device, and prevent possibility of tooth fracture caused byexcesslve hydraulic pressures from liquid lmprisonment at certain places within such devices.

Another object is to supply in such pumps and motors which have intermeshing' rotary pistons, wholly separated relief passages in the casings, whereby in their coaction the pistons maintain a' regular delivery of liquld through the'casing in each case without 1nterference entrapping of the liquid acted upon by either piston.

This application is a division of my Patent No. 1,799,237, granted April 7, 1931, for

rotary pump.

I have accomplished the aboveobjects 1n said devices by the means which are hereinafter described and claimed, and which 2 are illustrated in the accompanying drawing, in which Fig. 1 is an elevation of a rotary pump with its face-plate removed, having intermeshing pistons therein and having casing recesses or passages for cooperation with the pistons independently of each other for preventing entrapping of liquid in transit fromv a receiving to a delivery port. Fig. 2 is alike elevation, showing the same eleme'nts'but having a modified arrangement 'and'shape'of each of the sepa-,

rated passages in the casing.

It is to be understood, that the above exemplifications are illustrative only of the invention, and that other modifications may 40 be effected in the elements of the device shown which will accomplish my said purposes, without departing from the invention.

In the pumping device shown, in both.

along the longer diameter of the casing are the like pistons 15 having intermeshing projections hereinafter termed teeth 9, and mounted fixedly upon shafts 7 and 8, of which one may be power driven. In this type of'pump the teeth mesh in such a manner that the root closed cavities between them are alternately shifted from one piston to the other, so that a like but reversed pair of re-. lief passages 11 are employed in the abutting casing wall to successively and alternately receive liquid imprisoned in said cavities. The only difference-between the passages 11 of said Figs. 1 and 2 is inthe fact that the passages in the device ofFig. 1 are adapted to deliver liquid to a neutral area and conveyed to the discharge port 5, the device being reversible and therefore functions the same regardless of the direction of pump rotation.

The passages 11 in Fig. 2 are similar to those shown in Fig. 1, having each an annular part 11, which centrally alined but separated parts' 12 *from the other passage in each instance, but the outer and ,T-headed parts 14 of Fig. l'are diametrically alined with the parts 12, whereas in Fig. 2'the corresponding parts 14 are at a right angle to the said longer diametrical line of the casing, with angular outer terminations as shown, connected to the annular parts 11 by narrow parts or necks 13. The passages in Fig. 2 are thus contrived, shaped and employed only where the rotations of the pistons are unidirectional to deliver to one outlet. In

. Fig. 1, the arrangement is such, that the ports 6 and 5 respectivelybecome either receiving or discharge ports reversibly, when the direction of rotation of the pistons is reversed. 5 It is obvious that the neutral areas for reception of liquid from the root cavities may be positioned as desired relative to the different elements in coaction, and such relief means may be used with any rotary pump or motor without departing from my invention;

In practice, the pistons being in positive rotation, their meshed arrangement and coaction causes liquid to be drawn into the neutral area of the interior 4 of the casing to fill it, and be passed along between the teeth of the pistons to the opposite part of. the chamber to be delivered by way of the discharge port 5. However, in case no reliefpassages 11, 12 and 14 are provided, the practically;incompressible liquid becomes trapped as shown in Fig. 1 for instance between an end of an entrant tooth 9 of one piston 15 and the root cavity receiving said tooth of the other piston. A relatively great pressure is thus transmitted from the tooth 9 in question, by way of the entrapped liquid, to the piston 10 and its pintle 8 and in reaction to the other pintle or shaft 7, exert ing excessive friction on the pintles, and liable to cause breakage of the teeth.

Under normal conditions a good rotary pump of the ordinary type has a volumetric efliciency of from approximately 90 to Q6 per cent, the balance being lost due to what is termed slippage. A part of this slippage is due to the fact that the interdental spaces receiving liquid from the suction port of the pump do not become 100- percent filled. This is due to the fact that most rotary gear pumps usually must take liquid into the rotating'elements against opposing centrifugal force. The interdental spaces therefore which are receding from the suction port contain the larger per cent of liquid leaving a vacuum. Upon exposure to the discharge port the existing liquid pressure therein replaces the small spaces formerly occupied by the vacuum and intermeshing of the piston teeth begins, whereby the liquid is expelled into the discharge port excepting for the balance of the small percentage termed as slippage that becomes trapped between the teeth which are intermeshing, causing hammering, excessive wear, much loss of driving power, noise, vibration, and sometimes actual tooth fracture. The liquid then escapes into the suction opening.

' In my device, the liquid is led from the points where trapping occurs to a neutral area connecting with the tooth spaces that have just receded from the suction opening and which are not completely full, thereby permitting the liquid to pass thereinto at a, much reduced pressure which greatly diminishes the objectionable characteristics previously mentioned.

Comparative tests between rotary pumps supplied with such passages as above descri ed, prove that such passages serve to greatly enhance the efliciency of the devices in different ways. These tests show that the pumps supplied with these passages require eleven and three quarters per cent less operating power than the unsupplied pumps. Noise, vibration and hammering are immediately greatly reduced and possibility of tooth fracture for the aforesaid reasons made very remote.

Furthermore, in pumps handling very viscous liquids such as tar, glucose, malt syrups and lacquers which naturally "resist movement, the spaces between the teeth of the ropockets are almost completely absent, greatlydiminishing such harmful action as described.

As will be noted in Fig. 1, the outer terminations 14 of the relief passages because of their T-head shape, are never com letely spanned or covered by anyone tootii of a piston gear. The same applies to the device of Fig. 2. The reliefpassages thus may always discharge to-a neutral area in receiving at their inner ends 12. The passages are not in direct communication with each other at their inner ends 12, but spaced apart and thus each passage is used alternately, and no crowding is possible. v

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is: a

In a rotary pump or motor, an elongated casing having an inlet port and a discharge port and having arcuate opposite walls, like intermeshing piston gears rotatably mounted in the casing to contact with said arcuate walls circumferentally, the meshing teeth of said gears leaving an intermediate space containing liquid under compression, one side wall of the casing having an annular cavity around each gear axis w1th radial extension in each case to eifect a communication with said gear teeth spaces in turn, and each annular cavity having another radial extension at an angle to the first mentioned extension thereof, with each second mentioned radial extension having an angularly directed terminal part extending op osite to the forward direction of rotation of t e gear above it, said i angularly directed part being longer across each passing tooth of a gear than the transverse width of the tooth to deliver from said annular cavity into the inlet-port end of the casing by'way of the trapped spaces in turn between teeth of said gear which are in terminal contact with the adjacent arcuate wall of the casing.

In testimon whereof I aflix my signature.

A OS VERNER JENSEN. 

